Are the wheel studs actually firmly seated in the hubs? Make sure they're not loose. If they are, replace the worn part (either the studs or the hub itself may be screwed up). Also, make sure you're torquing down the lug nuts enough. Might want to invest in a torque wrench if you haven't already.

As far as the air bubbles....there is a bleeder screw....I think on the KA it's on the passenger side of the head, near the thermostat housing (someone correct me if I'm wrong...haven't lloked hard at a KA in a while). You will need to open that screw when the engine is cold, and run it for a little bit. You will need to repeat the process a few times (always waiting until the shit has cooled down before opening that screw again!).

Also, make sure your thermostat is actually opening (sometimes a new one can be bad).